Question for those in the know....

Are the leadscrews in all BPs the same(other than length)? I need a
new lead screw for my M head BP(30s era machine), and have found one
that came out of a newer J head machine(70s era machine).

If the diameter and pitch are the same, I can figure out the rest, but
wasn't sure if they would fit the same nuts/etc.

Thanks

JW